Apparatus for measuring wall thickness of propeller blades



1 0. J. DAVIS APPARATUS FOR MEASURING WALL THICKNESS Nov 9, 1948.

OF PROPELLER BLADES l0 Shee ts-Sheet 1 Filed May 24, 1945 W J J m w N mam m F m V r M i z r13 a w N0 3 3 g 3 ow Cm AW Q Q 9 m: P@ QQ Q v9 3 6 3F O N an. E Ta 2 2 N E n b 2 8 8 as 3 02 6 u: I I I l H L m a m I in 8 QM 3 3 w .1. 6 3 v 02 S E p 2 2 a: Q: ma 3,

Nov. 9, 1948.

APPARATUS FOR Filed May 24, 1945 D. J. DAVIS MEASURING WALL THICKNESS OF PROPELLER BLADES 10 Sheets-Sheet 2 INVENTOR. oQdmkL,

Nov. 9, 1948. D. J. DAVIS 2,453,306

APPARATUS FOR MEASURING WALL THICKNESS OF PROPELLER BLADES Y Filed May 24, 1945 10 Sheets-Sheet 3 INVENTOR.

v' wizd/ Q/a Nov. 9, 1948. D. J. DAVIS 2,453,396

APPARATUS FOR MEASURING WALL THICKNESS I OF PROPELLER BLADES Filed May 24, 1945 l0 Sheets-Sheet 4 INVENTOR.

$4M BY DAVIS APPARATUS FOR MEASURING WALL THICKNESS OF PROPELLER BLADES Nov. 9, 1948.

Flled May 24, 1945 10 Sheets-Sheet 5 INVENTOR. (wag QamL BY "oaw 2 J2 flag.

DAVIS Nov. 9, 1948.

'10 Sheets-Sheet 6 Filed May 24, 1945 o w 5 T T O 4 5 T ,w D 5 1 0 5 A M 9 .5 3 5 +6 5 o m 4 R J Nov. 9, 1948. v DAVls 2,453,306

APPARATUS. FOR MEASURING WALL THICKNESS OF PROPELLER BLADES Filed May 24, 1945 I 10 Sheets-Sheet '7 IN V EN TOR. ogwfla cd 9a W.

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Nov. 9, 1948. D. J. DAVIS APPARATUS FOR MEASURING WALL THICKNESS OF PROPELLER BLADES 1o Sheeis-Sheet 8 Filed May 24, 1945 v INVENTOR.

ogwza/cd oQdM fiw flab-neg Nov. 9, 1948. D. J. DAVIS 2,453,306

APPARATUS FOR MEASURING WALL THICKNESS ,OF PROPELLER BLADES Filed May 24, 1945 1o Shets-Sheet e v O HQ 20 45 4 v 45 u a i 4 INVENTOR. 59 oglg l fi/Cd w 11 rag Nov. 9, 1948.

'D. J. DAVIS 2,453,306 APPARATUS FOR MEASURING WALL THICKNESS v OF PROPELLER BLADES Filed May 24, 1945 7 1o Sheets-Sheet 1o Patented Nov. 9, 1948 APPARATUS FOR MEASURING WALL THICK- NESS F PROPELLER BLADES Dwillard J. Davis, Detroit, Mich, .assignor to Avco Manufacturing Corporation, a corporation of Delaware Application May '24, 1945, Serial No. 595,584

2'7 Claims. '1 The invention relates to apparatus for measuring the wall-thickness of hollow propeller blades.

The main object of the invention is to provide improved apparatus for expeditiously and accurately measuring the wall-thickness oi propeller blades.

Another object of the invention is to provide apparatus whereby the thickness can be measured of substantially all portions of hollow propeller blades which are provided with longitudinally curved or helical leading and trailing edges, or blades having faces of difierent contours.

Another object of the invention is to provide improved apparatus for measuring the wallthickness of hollow propeller blades in which the measuring mechanism is mounted on a carriage to travel longitudinally of the blade which includes adjustable supports for the ends of the blade which are adapted for blades of different lengths or widths and which are adjustable transversely of the blade and angularly for measuring the blade at points along different longitudinal lines and along the leading and trailing edges.

Another object of the invention is to provide measuring apparatus for measuring the wallthickness of propeller blades which is mounted on a carriage which is movable longitudinally of the blade and comprises counterweighted beams mounted on thecarriage for controlling the operation of a gauge mounted on the carriage.

Another object of the invention is to provide apparatus which is adapted to accurately measure the wall-thickness of hollow propeller blades.

Another object of the invention is to provide measuring apparatus for the wall-thickness of hollow propeller blades, which includes contacts engageable with the wall and gauge operating mechanism which is inoperative to apply excessive pressure at the contacts.

Other objects will appear from the detailed description.

The invention consists in the several novel features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings:

Fig. 1 is a front elevation of apparatus embodying the invention.

Fig. 2 is an end elevation of the apparatus viewed from the right end.

Fig. 3 is an end elevation viewed from the opposite end.

Fig. 4 is a plan, parts being broken away.

Fig. 5 is a longitudinal section of the device for supporting the tip of the blade on the table.

Fig. 6 is an end view of the device for 's'uppor-ting the tip of the blade shown in Fig. 5, the table being shown in section.

Fig, '7 is a perspective of the device for holding the tip of the blade.

Fig. 7 is a perspective of the holder for the shank of the blade.

Fig. 8 is a plan view of the device for supporting the shank of the blade.

Fig. 9 is a section taken on line ll"9 of Fig. 8.

Fig. 10 is a section taken on line lll--l 0 of Fig. 5.

Fig. 11 is a front elevation of a portion of the carriage, the carrier for the gauge and the devices on the carrier.

Fig. 1 2 is a section taken on Fig. 1 1.

Fig. 12 is a transverse section taken M -42 of Fig. 11.

line 12-42 "or on line Fig. 13 is a'vertical section illustrating the gauge and stem which operates the gauge.

Fig. 14 is a vertical section illustrating the contact engaging on the outer surface of the blade and the parts associated therewith.

Fig. 15 is a plan of a portion of the gauge carrier.

Fig. 16 is a perspective of the stem which operates the gauge.

Fig. 17 is a rear side elevation of a section of the longitudinally movable carriage and the device for locking the carriage against longitudinal movement and in spotted positions.

Fig. 18 is a section taken on line l8l8 in Fig. 1'7.

Fig. 19 is a perspective of the disassembled parts of the slip-connection between the hand-wheel and the screw for raising and lowering the gauge carrier.

Fig. 19 is a section illustrating said slip-connection in mechanism for raising and lowering the carrier which supports the gauge and the contact for engaging the outer face of the blade.

Fig. 20 is a plan view, partly in section, of the contact-carrying beams and the section of the longitudinally movable carriage on which they are pivotal'l'y sustained.

Fig. 21 is a section taken on line '2l- 2l of Fig. 20.

Fig. 22 is a diagrammatic perspective of the blade contacts for measuring the wall-thickness, the gauge and the signalling devices for indicating engagements of the contacts which engage the blade and the completion of a measuring operation.

The invention is exemplified in an apparatus which comprises generally: a supporting bed or 3 table; devices on the table for supporting, respectively, the tip and shank-ends of the hollow propeller blade to be measured; a carriage on which the measuring mechanism is supported and which is mounted on the table for rectilinear movement longitudinally of the blade; a pivoted beam-carried contact or feeler for engaging the inner surface of the blade and movable into the blade; a second contact-carrying beam mounted on the carriage outside of the blade and carrying a contact for operating the gauge; a carrier with a gauge mounted thereon for vertical movement on the longitudinally movable carriage and operable by a contact on the second beam; a contact or feeler movable longitudinally with the gauge-carrier and movable vertically thereon for engaging the outer surface of the blade in vertical alignment with the contact on the inner beam; a gauge-operating element vertically movable in the gauge carrier adapted to be engaged by the stop on the outer beam; mechanism for lowering the carrier to measure the wall-thickness of the blade between the contacts engaging the 'inner and outer surfaces of the blade; counter-balancing means applied to the beams for holding the contacts thereon in engagement with the inner surface of the blade and for operation of the gauge, with a predetermined pressure; and devices for indicating when the blade-engaging contacts are engaged with the blade.

The supporting structure for the apparatus comprisesz a frame 39 built up of structural parts including on its topthree longitudinal I-beams 3 I a bed or table-section 33 on which the device for supporting the shank-end of the blade is mounted; and a table or bed-section 34 on which the device for positioning nd supporting the tipend of the blade is mounted. v

The propeller blade :1. is supported with its longitudinal axis extending longitudinally of the table by a device which is adapted to receive the shank of the blade and a device for supporting the tip-end of the blade. The device for sup porting the shank-end of the blade comprises: a semi-cylindrical chuck-member 41 (Fig. 7 which is mounted in a block 48 and a base or bracket 49 on which the block 49 is supported and which is provided with side-members 50 which are slidably guided in stationary guides on the table-section 33, for adjustment of this supporting device longitudinally of the table. Chuck member 4'! has fixed thereto a semi-cylindrical member 54 which fits in an arcuate channel 55in block 48. Block 48 is provided with a vertical trunnion 58 which fits in a bearing in base 49 and permits block 48 to rotate horizontally on said base. A plate 59 is secured to the lower end of stud 5'? and engages an annular shoulder 60 in bracket 49 for retaining block 43 on base 49. A stud 63 extends vertically through the base 49 at one end thereof and through an elongated slot 64 in'the table-section 33, is provided with a head 65 at its lower end for engaging table-section 33 and a screw-handle 66 whereby the stud may be tightened to clamp the base 49 in its adjusted position longitudinally of the table. Calibrated lines 61 (Fig. 9) are provided on one of the guides 5! to indicate the longitudinal position of the bracket 49 and member 41 on the table. A pin 69 extends vertically through a hole in the bracket 49 and is adapted to enter any of a series of holes in table-section 33 to longitudinally spot the chuck-member 41 for the blades of different standard lengths. Wear plates 41' are provided in the upper face of member 41 on which the shank of the blade is adapted to rest. This construction exemplifies a device which is adjustable longitudinally of the blade for supporting blades of different length, and in which the chuck-member is horizontally rotatable to permit the shank end of the blade to be shifted angularly in a horizontal plane relatively to the measuring mechanism for measuring points along the edges of the blade.

The device for supporting the tip-end of the blade over the table comprises a socket 14 (Figs. 5 and 6) in which is confined a block 16 which is divided on its horizontal center. Block 16 is preferably of fibre and the contiguous faces of its sections are notched to form a transverse groove 11 withan inwardly curved end, which is adapted to receive and fit around the curved tip of the blade. The sections of block 16 are held to permit a slight angular movement in socket 74 by a pin 18 which extends vertically through socket 14 and the sections of the block 16. Shoes 190 provided with grooves I 9! in which the tip of the blade fit are secured to stems I92 which are threaded to lugs I93 which are fixed to socket 14. Socket I4 is supported for movement longitudinally of the blade on and for rotation around a cylindrical-stem 19 on a shaft 8! The outer end of stem 19 is provided with a washer 8D for limiting the sliding movement of socket 14 on stem 19. Shaft 8! with its stem 19 is slidably adjustable longitudinally of the blade in a bracket 82 in which said shaft may be locked in difierent positions by a clamp-screw 83 which is adapted to enter recesses 84 along the shaft 8|. screws 92' in bracket .82 extend into grooves inshaft 8l to hold said shaft against rotation. A spring85 is interposed between socket 14 and shaft 8| to press the block 16 into snugly fitting relation with the tip of the stem and to permit the block to be disengaged from the tip of the blade. Bracket 82 is mounted for sliding adjustment transversely.

of the table in guides 82 Bracket 82 is provided with rollers 86 for engaging the inner faces of guides 82 which are fixedly secured to the tablesection 34. A stop 81 is secured to table-section 34 for limiting outward movement of bracket 82. Socket i4 is rotatable on stem-portion 19 of shaft 8i to permit the groove in block 16 to be rotated on its axis to conform to the helical angle on the tip-end of the blade. This exemplifies a transversely adjustable device for supporting and positioning the tip-end of the blade for different angular positions relatively to the measuring device hereinafter described.

The mechanism for measuring the wall-thickness of the blade is supported on a carriage gen. erally designated 2), which is movable longitudinally of the table and the blade. 1) comprises: a section or frame 36 on which the gaugeand associated parts are'supported; a section or frame 31 on which are supported the tilting beams hereinafter described which respectively carry a contact or feeler for engaging the inner surface of the blade and a stop for controlling the gauge or mechanical dial indicator and a rod 38 which eXtends between the sections 36 and 31 connects them for conjoint travel longitudinally of the table. The carriage is adapted to travel on a v shaped rail 39 which is fixedly supported on the longitudinal center of the table and a fiat rail 40 secured on rear side of the table. Each of the sections 36, 31 is provided with a pair of V- rol1ers 42 adapted to run on rail 39 and with a pair of rollers 43 adapted to run on rail 40.

The measuring mechanism forthe wall-thick-- This carriageit -nes's of :the hollow fialade a amounted on (the roarmiage lb comprises: ;a beam :90 which :is adapted to extend through the izbore .;of {the :shank of the Jalade :into Ethe :hollowzblademaud is provided-with a -contact or feelerf'al :adap'ted 'tolengage theinner face of the wall H3O Z be'measurediin thickness, and a beam 92 which extends outwardly :01? the :blade and carries .at its :distal .end :a stop .9.13 "which ris adapted ito :be engaged iby the .gaugeeoperating :means hereinafter described. .Beams 90 and 19:2 extend longitudinally of the :path of travel :ofthe carriage b. Beams fBfi and 92 eQFigs. .20 and .121) are eachsecuredto 'membersz'95 and bothlof said members are clamped toearcross-shaftlfixwhiclnis 'journalled iin anti-friction bearings 9;! .in pedessurensaypsix to eight ounces, against-the inner :fa'ceoffthablade.during thezmeasuring operation. Astop-screyv IIiQ'is'screW-threaded to rod I and isradaptedrto'engage a stop IN on carriage'sec- .ti'on :31 for norm-ally positioning beams 9.0 and -92. vThe:portionoi'beam fill'whichzisadapted to enter tthe hollow propeller blade is preferably taperedtowardits.contact:9I so that it-can engage =the1innerzface of i the 'blade in the narrow portions of 'xthe space in the blade adjacent :the leading :and trailing :edgesand at %the tip. .-A flash-pot comprisesra cylinder .106 mounted-.1021 the rod .38 O'f1the longitudinally :movablercarriage b and a piston :18? in said cylinder which is-provid-ed :with "a stem IE8 which issecured 1byza1clamp 1:09 to 'beami92, and this dash-:pot'cushionsthe pivotal movementsof beam 29!], 82. This exemplifies a pair of counter-weighted :beam-s pivotally mounted onthe carriage handsecuredatogether ffor=conjoint tilting,.one 'of 'which is adapted to .extend :into the :blade land carries a contactor feeler for *engagingthednner surface of :the blade and an outer beamxwhich carries :a stoplcontrolled by the contact on 'the inner beam forengagement by the gauge-operating'means. The longitudinally movable carriage 2) maybe locked:in..-spotted positionslongitudinally of the table or propeller blade (by a device which comprises KFlgs. 12,117 "and 18),' a'levenIM onashalft IIE-which-is fulcrumed on carriage-section 'tfi, and arm H6 .on

isaid'shait, and-provided with a conicaleended stud :adapted to enter sockets H 1 in the rear of rail 40, a spring :IIII applied to arm .116 "for folding thesstu'd normally engaged with "rail .40, and a '-spring'-fp-ressed':bolt 'I I9 carried by lever H4 is :a'dapte'd to engage alatch I 20. on carriage-section #36 :for :locking ilever .li III .inits carriage-releasing yposition.

Aagauge-suoh as-a mechanical dial indicator lltilrwhich' is calibrated to indicate measurements m'f twal-lethickness :is :mounted :on .a carrier II. I' .Wliichris .zslidably mounted on upstanding Lposts H52, the. lower :ends zofwhich are fixedly-secured :inrthecerrriage-section 3.5. .A stem 1241s carried iin aaslceve Is2rofiinsulated materiaL. and isproivi-cled avith :a :contact orzfeeler I ;215 ;for engaging ut out-erasurface :of the propeller "blade in sub- .stantial eaxial alignment with contact or 'feeler .8 I- onwthe beam 190. .:A: spring I-2r'I :in sleeve I26 en a es-an; annular shoulder I 2 8 .on stem I I 24:,and zholdslthereonta-ct: I normally-rim aiprcdetermined :nos'ition avertically ,withgrespect to :the [carrier di ii Sleeve "I 2 6 .isfixedlysecuredin a section 1530 which sis s-seoured itoaand vertically movable w h the carrier I I I so that the contact I25 will beimovable vertically ,wi-thigauge .1 I10 and carrier rIrII. Conitact I 25 and stem I24 are adapted to :position learner -:l M and the gauge H0 carri th reby according .to the thickness of the :blade between contacts .9 I and :I 25.

The means :for operating the gauge .1 III .coml-prises: astem I whichis provided at its lower end with a :oontact .I5I adapted to engage the stopzQS on the beam 92 and is slida-bly mounted .dn essleeve (I52 .Wlhichiis fixedly held in carrier -.I-I1I :a spring Ii5 -3 between ;a cap-plate I54 and a shoulder L55 on {stem I580 for yieldingly holding contact I 5-! in :a predetermined "vertical position carrie-r IqIii' and which permits stem I50 to .be shifted by=stop:,9,3 ;on:beam;92 tooperate the. gauge 'I-Ill :whichis provided with a springapressed depend n -Stem H56 which vengages the upper end cistern 4:50.. Eheilfirtical movementof contact iI:.5,-I vand stem 50 relatively :to the contact causes :the cause "I I0 to be actuated by stem .correspondinglyitoythe wall-thickness ofthe blade in between :con'tacts $91 and I25. :Stem infill is termed of two sections screw-threaded :together and {is :provided with 3110165 -.I.6-I' an d flat surfaces IifiZ son lits zoliter periphery ito ,reduce weight and friction .between the stem I150 and sleeve :I:5 2. Qa-rrier 'II I, gauge M50, contact 4,2,5, and the .l-gaugee-operating ;means ;are :movable vertically rto :move the contact 125 into and out :of engage- ;ment with the .outer .face "of the propeller blade by amechanism filig- :.12?) which com ises: screw-sl1aft 1:32, the lower end of which ;is ,jou-rnailed inanti-zf-riction bearings I33 incarriagesection :36. Shaft A32 has :a screw-threaded con- 'nection with collars -I.-34;and I35whioh are secured to l carrier IFIaI -.so that-rotation of said shaft will .rai-seorilower the carrier I II. Shaft :32 is rotatable {by-1a hand-Wheel 1:36 which is rotatably :mounted 'on and connected to the upper end of shaft for-rotationof-the shaft by aslip-conrnection which causes rotationof said shaftzby the hand-wheel it-o be discontinued when the Contact l25 engages the outer surface of the blade to prevent :such engagement .With excessive pres- .surerof .marring. oftheblade by said contact. This slip-connection comprises (Fig-s. 19,19 a'collar :I'38 which is secured to rotate with the hub of hand-wheel 4:36 and provided on its upper face with clut-ch-teeth'having one of their sides in- ;clined; a collar +39 slidably connected by splines I410 to the stem MI on .the upper :end o S aft 132 and provided onits under face with clutchteeth having goo-acting :inclined sides and inter :fitting twithwthe clutch teeth on collar I38; a spring M2 for 'yieldingly pressing clutch collars 51.39 and I348 intointerfitting relation, and per- ;mitting them to .slip I in one .rotative direction; a :flanged. :ring \IAB engaged by the upper {end of spring 442; 217111117144 for positioning'ring I43 on stem ;I-,4-I .and a locking-nut I45 for nut I44;

This sslipeconnection .acan be adjusted by 1 the adjustment'of the's'pring I42 sothat when contact 112.5 :is ilowered into engagement with'the outer surface of the propeller blade the vertical move- :mentofca-rrier I IEI will-be arrested and continued irotationof theEhand-wheel I36 will not increase :;the.;press.ure:of contact" [2.5.- againstthe outer surface of "the propeller blade. .A stop lH is fixed torcarriage-section :36 (Fig. -12 for limiting the upward -;movement 50f :Qarrier I;I,I :beyond ,a :predetermined limit. A sleeve 90 composed ofsec- I25 are engaged with the inner and outer surfaces of the blade, respectively. For this purpose, a stem I65 (Figs. 12 and 14) is sli-dably mounted in a sleeve I66 which is insulated as at I61 from the carrier section I38 and said stem is normally pressed downwardly by a spring I68 to engage an adjustable stop I69 on its upper end and sleeve I65. Stem I65 is provided at its lower end with a contact I16 which is engageable by the stem I24. A stem III, provided at its lower end with a contact I72 engageable by the upper end of stem IE5, is slidably mounted in a sleeve I73 which is insulated at IM- from the bracket I3Ii on the carrier-section Hill and is normally pressed downwardly by a spring I76 to be arrested by a nut [75. The stems I24, I85 and III are electrically connectedto a circuit as illustrated in Fig. 22. Lamps I84 and I87 are actuated from a power circuit including conductors I80, I8I and transformer I82. Lamp I84 is connected by a conduc tor I84 to stem I24 and by conductor I83 to the transformer I82 which is connected by conductor I85 to contact SI for a circuit through the blade. Lamp I8'I is connected by a conductor IBI to stem I55 and by conductor I83 which is connected to the transformer I82 and is actuated when stem I65 engages stem I24 from which cur-rent passes through the blade to contact III and conductor I85 which is connected to the transformer I82. When contact 9| does not engage the blade, lamps I84 and I8? may both be actuated when sufiicient downward movement or pressure is applied to the carrier III to engage stems I24,I65 and III. Current will then flow through conductor I83, lamp I84, conductor I84 to stem I25 and through lamp I8l from conductor [83' through conductor I81 to stem I65 and from stems I24 and I65 to stem Ill and thence through conductor I85 to the transformer I82.

The operation of the apparatus is as follows: The propeller blade (1 to be measured is placed with its tip-end in the groove ll of block I6 and I its shank-end is laid in the chuck-member 41. In this placement of the blade, the spring 85 will permit socket I4 to move longitudinally until the shank-end is located in the chuck-member and will yieldingly hold block I6 in engagement with the tip of the blade. The devices for supporting the shank and tip, respectively, may be adjusted longitudinally of the t'able'to receive and hold blades of different lengths. The stem or shaft SI which carries socket I4 and block I6 may be shifted longitudinally in bracket 82 and locked therein by tightening the screw-handle 83 in the notches 84. The shank supporting chuck-member 4'! may be adjusted longitudinally of the blade, upon loosening screw-handle 66 on screw 63 and removing pin 66, to the desired position for supporting the blade. Upon tightening handle 65 the chuck-member ll will be secured against longitudinal movement. The measuring mechanism on the carriage b ismovable longitudinally of the blade for longitudinal movement and measuring wall-thickness at difierent points in a longitudinal line of the blade while the tip and shank-supporting devices are left in their longitudinally adjusted positions.

8 In order to position the blade with its longitudinal axis angularly .to the movement of the carriage 36 for locating the contact 9| for measuring the Wall-thickness at points between the longitudinal center of the blade and its edges, the tip-supporting device is adjusted transversely which will cause the blade and. its shank-holder to swing horizontally on the axis of the trunnion 51 for the'block 48 which supports the chuckmember 54. .By moving the carriage 3B for the measuring mechanism longitudinally and the angular setting of the blade, the contact 9| may be positioned to measure the wall-thickness in any portion of the blade faces.

In order to measure the wall-thickness at points in some spots of hollow blades which usuall have longitudinally curved. leading and trailing edges, it is necessary to shift the blade-supporting devices so the beam 98 can extend into the hollow blade in a horizontally angular direction relatively to the longitudinal axis of the blade. This may be done by relative transverse adjustment ofthe tip-supporting device and pivotal movement of the shank-supporting device. The trunnion5'l on guide-block 48 permits horizontal angular movement of chuck-member 4! for this purpose, and the pivot pin I8 permits the block I6 to move angularly. By means of these adjustmentsof the tip-supporting and shank-supporting devices, blade a may be shifted relatively to position contact ill on beam 88 to measure the wall-thickness in substantially all portions of the blade faces. Socket I4 which carries the tip-holding block 16 is rotatable on stem 19, and the shank is rotatable on the chuck-member 47 to permitrotation of the blade on its longitudinal axis for positioning contact 9! sothat it will engage the inner face of transversely curved face positions of the blade on axes substantially perpendicular to said surfaces. In setting the measuring mechanism, the gauge III! is adjusted to register Zero when the contact or feeler 9| engages the contact I25. When the mechanism is once adjusted in this manner, the measuring operations will result in indicating the wall-thickness on the gauge IIIl. At the commencement of the measuring operations for a blade, the carriage b ismoved to the right hand end of the table with the beam IlIi outside of the blade where it will pass through the opening in the shank of the blade. The carriage b is then moved left to bring the cont-act III on beam 58 .to the point to be measured. The gaugecarrier III is normally maintained in its raised position. When contacts 8i and I25 have been moved longitudinally to a spot to be measured, the operator will rotate hand-wheel I56 to operate screw-shaft 32 and lower the carrier III.

When the carrier I II is lowered for a measur ing operation, contact I25 will engage the outer surface of the blade. A circuit will then be established through conductor I83, lamp I84, conductor I84 stem I24 and contact I25, the blade, contact SI and conductor I85. Lamp I84 will then be energized. If carrier III is urged downwardly with continued pressure against the blade so as to overcome the zero setting of dial indicator IIII, the stem I24 is forced upwardly and engages contact III) on stem I65 to close a circuit through conductor I83, lamp I81, conductor I81, stems I85, I24, contact I25, the blade-contact III and conductor I85. Lamp I8I, which is usually of a different color for differentiation from lamp I84, will provide a warning signal of this excess pressure. Adjustment of the carrier III slightly upward'will open the circuit for'lamp I8I between 9v stem I524. and contact '31-0 and: indicate thatv the excess pressure has been removed. Since engagement: of contact SI with the inner surface of the. blade cannot be otherwise determined, provision is made for simultaneously energizing both lamps I84 andv l-8'I. If there is no engagement of contact 94 and thablade, the circuits for lamps I84, I81 will be open. Continued downward movement of carrier II I will increase the pressure of stem I24: and its contact against the blade and force stem IIZ l. upwardly and shift stem I65 to engage contact: I12 on stem I'II. Both lamps 84,. I18?! .will then be energized without engagement of contact 9i and the. inner face of the blade; The circuit for lamp I81 will be through conudctor I83, lamp I81, conductor I8I stems I185, Ii'I I, and conductor I85. The circuit for lamp I8'k will be through conductor I83, lamp I84, conductor IBM, stems I24, I65, I11, and conductor I85. The simultaneous operation of both lamps I84, I81 will indicate the failure of contact 9| to engage. the inner face of the blade. Lamp I84 indicates ordinary reading conditions and lamp I281 slight overpressure. The operator can distinguish the variance and adjust the measuring mechanism sowthatthe circuitfor lamp I84 closes when contacts QI: and; I25 engage the inner and outer faces of the blade. If, however, contact 9i does not engage the blade, the continued lowering of the carrier III will increase the pressure on stem I124 and close the circuits for both lamps Ii84=, lfifl'through stem I'I I as an indication of the lack of engagementof" contact SI and the inner face of the blade; or i'fsuch pressure is applied,

the lamps will not be actuated. In practice, the

normal clearance between stems I24 and I65'may be .002 inch and that: between stems I65 and Ill may be .015 inch. If objectionably excessive downward pressure is applied to. the carrier III,

the slips-connection. between shaft. I3? and handwheel Itfiwill prevent further lowering movement of the carrier III by the hand-wheel I36. The wall-thickness at substantially all points of both faces of the blade may be successively measured by setting of the carriage and relative setting of the blade-supporting devices. By longitudinal movements of the carriage and the setting of the blade-supporting devices into different transverse and angular positions relatively to beam 90, the

contact. 9.1 may be positioned to engage-and meas- Y ure points near the curved leading and trailing edges of the. plate and in the tip. After the wall thickness of one of thefaces has been measured, the; blade can be. rotated for measuring the other face. cessi'vely measured while the carriage 1) remains locked at each longitudinal station by transverse adjustment of the supporting device of the blade. A longitudinal series of spots may be successively measured by moving the carriage b longitudinally relatively to: the blade. During these measuring operations; the counter-Weights 99 will at all times urge. the contact 9I' against the inner faceof the blade with a limited pressure. The counter-weights $39v may be adjusted to cause contact 9:1? toexert an upward vforce of from three to ten ounces. The narrow spaces between the bladefaces adjacent the tip of the propeller blade necessitates; the use of a beam 90- which lacks suflici'ent: inherent rigidityfor avoiding deflection stresses. The low degree of pressure exerted by the contact 9| against the blade results in substantially uniform deflection in the beam at all times. The; load; imposed upon the. beam 92' by the-spring" I53 will be substantially uniform. As

A transverse series of points may be suca result, when the measuring mechanism. is once correctly adjusted toind i'cate zero, the inherent deflection of the beams will remain uniformand the measurement of the wall-thickness will be truly indicated on the gauge".

The invention exemplifies apparatus for measuring the w all-thi'clm-essof hollow steel propeller blades which: canbe expeditiously operated and which: Willi accurately measure the wall'sthickness. The invention also. exemplifies an apparatus which: provides: for relative; movement of the measuring mechanism and theblades, for measusing the Wal'l'f-thicltness of blades: of different shapes and lengths.

The invention: is not to be understood as re striated. to; thfii details set forth, since these may be within the scope of the appended claims: without departing from the spirit and scope the invention.

Having thus described the invention, what I claim as. new and desire to secure by Letters Patentiisc 1. Measuring apparatus for the=wall thickness of-hollow propeller bladescomprising-z devices for supporting the tip and shank of the blade; a carriage mounted for movement" longitudinally of the: blade; mechanism for measuring thewallthicknessmouniz'ed on: and movabl'elongitudina-Ily with the carriage, includinga beam adapted to extend intothe blade andcarrying a contact for engaging the innerface of the blade wall; and means for adjusting the supporting devices to support the blade relatively to the contact on the beam. for engagement of said con-tact with substantially anyportionof the-inner faceof' the a. carriage mounted for movement longitudinally of the: blade; mechanism: for measuring: the Wallthicknesszmounted on. and movable longitudinally with the carriage, including a beamadapted to' extend into the blade and carrying a contact for engaging the inner face of the blade-wall; and means; for individually adjusting the supporting devices to supportthebladerelatively to the contact on the beam for engagement of the contact with. substantially any portion of the inner face of the. blade walll.

. 3*. Measuring: apparatus for the wall-thickness of hollow propeller blades comprising: devices for supporting the tip andshank of the blade; a carriage mounted for movement longitudinally ofthe. blade; mechanism for measuring the wallthickness mounted onand movable longitudinally with. thecarriage, including; a beam adapted. to extend into the blade and carrying a contact.

substantially anyportion of the. inner face of the bladewvall, one of'said devices being provided. with spring-means for urging the blade toward the other device.

' 4. Measuring apparatus for the. wall-thickness of hollow propeller blades comprising: mean for supporting the blade; a carriage mounted for movement longitudinally of the blade; and mechanism formeasuring the wall-thickness mounted.

on and movable longitudinally with the carriage and including a pivoted beam. adapted. to extend.

into the bladeand carrying a contact for engage ing the inner face of the blade-wall, a second 1 l beam pivotally movable with said other beam adapted to extend outside of the blade and carrying a stop co-related to the contact on said other beam; and a counterweight for pivoting the inner beam to engage its contact with the inner face of the blade.

5. Measuring apparatus for the wall-thickness of hollow propeller blades comprising: means for supporting the blade; a carriage mounted for movement longitudinally of the blade; mechanism for measuring the wall-thickness mounted on and movable longitudinally with the carriage and including a pivoted beam adapted to extend into the blade and carryin a contact for engaging the inner face of the blade-wall, a second beam pivotally movable with said other beam adapted to extend outside of the blade and carrying a stop co-related to the contact on said other beam; a counterweight for pivoting the inner beam to engage its contact with the inner face of the blade; and means for adjusting the counterweight to vary the pressure of said contact blade and carrying a stop co-related to the contact on the beam which extends into the blade, and a dash-pot between one of the beams and the carriage.

'7. Measuring apparatus for the wall-thickness of hollow propeller blades comprising: means for supporting the blade; a carriage mounted for movement longitudinally of the blade; mech'ae nism for measuring the wall-thickness mounted on and movable longitudinally with the carriage,

including a pivoted counter-weighted beam adapted to extend into the blade and carrying a contact for engaging the inner face of the blade wall; a second beam adapted to extend outside of the blade and carrying a stop co-related to the contact on the beam which extends into the blade; a signal device; and means including the said contact for actuating said signal device.

8. Apparatus for measuring the wall-thickness of hollow propeller blades comprising: means for supporting the blade; a carriage mounted for movement longitudinally of the blade; a pivoted beam on the carriage adapted to extend into the blade and provided with a contact for engaging the inner face of the blade-wall; a second beam on the carriage, movable with said other beam, outside of the blade, and provided with a stop; a. gauge; gauge-operating means; a contact for engaging the outer face of the blade-wall; and a vertically movable carrier on which the gaugeoperating means is operable by said stop and on which the gauge and outer contact are mounted.

9. Apparatus for measuring the wall-thickness of hollow propeller blades comprising: means for supporting the blade; a carriage mounted for movement longitudinally of the blade; a pivoted beam on the carriage adapted to extend into the blade and provided with a contact for engaging theinner face of the blade-wal1; a second beam on the carriage, movable with said other beam, outside of the blade; andprovided with a stop;

a gauge; gauge-operating means; a contact for engaging the outer face of the blade-wall; a vertically movable carrier on which the gauge" operating means is operable by said stop and on which the gauge and outer contact are mounted; and screw-means for raising and lowering the carrier for engaging'the contact carried thereby with the blade and shifting the operating-means to operate the gauge.

10. Apparatus for measuring the wall-thickness of hollow propeller blades comprising: meansfor supporting the blade; a carriage mounted for movement longitudinally of the blade; a pivoted beam on the carriage adapted to extend into the blade and provided with a contact'for engaging the inner face of the blade-wall; a second beam on the carriage, movable with said other beam, outside of the blade, and provided with a stop; a gauge; gauge-operating means; a contact for engaging the outer face of the blade-wall; a vertically movable carrier on which the gauge-operating means is operable by said stop and on which the gauge and outer stop are mounted; and means for raising and lowering'the carrier for engaging the contact carried thereby with the blade and shifting the operating-means to engage the stop for operating the gauge.

11. Apparatus for measuring the wall-thickness of hollow propeller blades comprising: means for supporting the blade; a carriage mounted for movement longitudinally of the blade; a pivoted beam on the carriage adapted to extend into the blade and provided with a'contact'for engaging the inner face of the blade-wall; a second beam on the carriage; movable with'said other beam, outside of the blade and provided with a stop; a gauge spring-pressed gauge-operating means; a contact for engaging the outer face of the bladewall; a vertically movable carrier in which the gauge-operating means is slidable by said stop and on which the gauge and outer contact are mounted; and means for'raising and lowering the carrier for engaging the contact carried thereby with the blade and shifting the springpressed operating-means to engage the'stop for operating the gauge.

12. Apparatus for measuring the wall-thickness of hollow propeller blades comprising: means'f-or supporting the blade; a carriage mounted for movement longitudinally of the blade; a pivoted beam on the carriage adapted to extend into the blade and provided with a contact for engaging the inner face of theblade-wall; a second beam on the carriage,m0vable with said other beam,

outside of the blade and provided with a stop;

a vertically movable carrier; a gauge mounted on the carrier for vertical movement therewith;

a contact carried by the carrier for engaging the.

outer face of the blade;,a stem, carried by and slidable in the carrier and engageable' with the stop for operating the gauge; and means forraising and lowering the carrier to engage the contact thereon with the-blade and shifting the stem so as to be operated by the stop.

beam on the carriage adapted to extend into the blade and provided with a contact for engaging 1 the inner face of the blade-wall; a second beam on the carriage, movable with said other beam, outside of the blade and provided with a stop; a gauge; spring-pressed gauge-operating means; a

contact for engaging thejouter face of the b1ade-==- Walt; a. vertically movable. carrier on which the of hollow propeller blades comprising means: for,

suppo'nting-t the. blade;- a carnage mounted for movement longitudinally of the blade; 2,. pivotedbeam on the carriage adapted. to extend into the blade and provided with a. contact for engaging the: inner face of. the blade-wa-li; a second. beam; on the. carriage, movable. with said other beam; outside of the blade and. provided with a. stop; a, carrier slidably mounted for vertical: movement; a. gauge mounted. on and movable with the car her; a contact, mounted. on the carrier, for engaging the: outer face: of the blade; at springpressed stem carried? by and' slidably mounted in the carrier for operating the gauge, by engage:- ment with the stop; and means for raising: and: lowering the carrier. 1

15; Measuring. apparatus for firewall-thickness of hollow propeller blades. comprising: devices for supporting the tip and shank. of the" blade; re-- spectively; a carriage mounted for movement longitudinally of the blade; mechanismformeas uring theWall-thickness mounted on and movable longitudinally with the. carriage including a beam adapted to extend into the blade and carrying a contact for engaging the inner face of the bladewall; and means for adjusting the supporting devices to support the blade relatively to the contact on the beam for engagement of said contact with substantially any portion of the inner face of the blade-wall, the shank-supporting device comprising a chuck-member on which the blade is rotatable on its longitudinal axis, the tip-supporting device comprising a rotatable tipengaging member.

16. The combination with apparatus mounted on a carriage for movement longitudinally, and

measuring the wall-thickness, of hollow propeller blades, comprising: a beam'mounted on the carriage for longitudinal movement therewith and adapted to extend into the blade for contacting the inner face of the blade-wall; of means for supporting the blade to extend longitudinally of the travel of the carriage; and means for adjust-- ing the supporting-means transversely of the beam for measuring diiferent portions of the blade-wall.

1'7. The combination with apparatus mounted on a carriage for movement longitudinally, and measuring the wall-thickness, of hollow propeller blades including a beam mounted on the carriage for longitudinal movement therewith and adapted to extend into the blade for contacting the inner face of the blade-Wall; of means for supporting the blade to extend longitudinally of the travel of the carriage; and means for adjusting the supporting-means transversely of the beam for measuring difierent portions of the blade-wall.

18. The combination with apparatus mounted on a carriage for movement longitudinally, and

measuring the wall-thickness, of hollow propeller blades including a beam mounted on the carriage for longitudinal movement therewith and adapted to extend into the blade for contacting the inner face of the blade-wall;, got means for supporting the blade to extend longitudinally of 14 the. travel of. the carriage; and means for adjust.- ing the supporting-means transversely oil the beam for measuring di-ilie'rent: portions of the blade-walla; and means for adjusting; the supporting in cans. longitudina 11y.v

19a The combination with apparatus mounted on a carriage for movement longitudinally,. and: measuring the. WEIHthlG'lCIlSS,. of hollow: propeller blades including a beam mounted on carriage for longitudinal movement therewith and adapted to: extend into'th-e. blade. for contacting the inner face of the: blade walt; on a? device for supporting. the shank of the blade: device: for supporting the tip of the blade; and means. flor adjusting-the tip supporting device transversely to the beam and pivoting the: shank supporting device, for measuring the: wall-thickness of. di-iiferemt, portions of. the walls of the blades.

20. The combination with apparatus mounted: on a. carriage: for movement longitudinally. and measuring thewa1l-thick-ness,.of hollow propeller blades including; a. beam mounted on the car- Iii-age. for longitudinal movement and adapted to extend into the blade for contacting the inner face of the blade-wall; of a] devicev for supporting. the shank of. the blade; a. device. tor supporting. the tip. of the blade; and. means for adjusting. the the supporting. device transversely and pivoting. the shank supporting device to support the blade angul'arly relatively to the beam,, for measuring the wall-thickness of different portions of' the walls ofthe blades.

21. The combination with apparatus mounted on a carriage for movement longitudinally, and measuring the wall-thickness, of hollow propeller blades including a beam mounted on the carriage for longitudinal movement and adapted to extend into the blade for contacting the inner face of the blade-wall; of a device for supporting the shank of the blade; a device for supporting the tip of the blade; means for adjusting the tip supporting device transversely relatively to the beam and pivoting the shank supporting device for measuring the wall-thickness of different portions of the walls of the blades; and means for relatively adjusting the devices longitudinally for holding blades of different lengths.

22. The combination with apparatus mounted on a carriage for movement longitudinally of and measuring the wall-thickness of hollow propeller blades including a beam mounted on the carriage for longitudinal movement and adapted to extend into the blade for contacting the inner face of the blade-wall; of a device for supporting the shank of the blade; a device for supporting the tip of the blade; and means for adjusting the tip supporting device transversely and angularly relatively to the beam and pivoting the shank supporting device, for measuringthe wall-thickness of different portions of the walls of blades; and means for adjusting at least one of said devices longltudinally for supporting blades of different lengths.

23. The combination with apparatus mounted on a carriage for movement longitudinally, and

measuring the wall-thickness, of hollow propeller blades including a beam mounted on the carriage for longitudinal movement and adapted to extend into the blade for contacting the inner face of the blade-wall; of a device for supporting the shank of the blade; a device for supporting the tip of the blade including a block having a groove for receiving the tip-end of the blade and springpressed jaws for engaging the blade adjacent to the blocks; and means for transversely adjusting 15 the tip supporting device and pivotally supporting the shank supporting device.

24. Measuring apparatus for the wall-thicknessof hollow propeller blades comprising: a gauge; contacts for engaging the. inner and outer faces of the blade-wall; means for operating the gauge. controlled by the engagement of said contacts with the blade-Wall; a vertically movabl carrier on which the outer contact, the'gauge, and the gauge-operating means are mounted; and means including screw means for shifting the carrier with the gauge, gauge-operating means. and the outer contact thereon, including an element for rotating the screw-means and a one-way slipconnection for preventing further movement of the carrier and limiting the pressure of the outer contact against the blade-wall.

25. Measuring apparatus for the wall-thickness of hollow propeller blades comprising: a gauge;

contacts for engaging the inner and outer faces of the blade-wall; means for operating the gauge controlled by the engagement of said contacts with the blade-wall; a vertically movable carrier on which the outer contact, the gauge, and the gauge-operating means are mounted; and means for shifting the carrier with the gauge, gaugeoperating means, and the outer contact thereon, including a screw, an element for rotating the screw and a one-Way slip-connection between said element and the screw for preventing further movement of the carrier and limiting the pressure of the outer contact against the blade-wall.

26.'Measuring apparatus for the wall-thickness of hollow propeller blades comprising: a gauge; contacts for engaging the inner and outer faces of the blade-wallymeans for operatingthe gauge controlled by the engagement of said contactswith the blade-wall; a vertically movable carrier on which the outer contact, theg'auge. and the gauge-operating means are mounted; a

. stop controlled by the contact engaging the inner face of the blade, engageable b theoperating means; a signal device; and means controlled by the contact engaging the outer face of the blade, for controlling said signal.

27. Measuring apparatus for the Wall-thickness of hollow propeller blades comprising: a-gauge; contacts for engaging the inner and outer faces of the blade-wall; means for operating the gauge controlled by the engagement of said contacts with the blade-wall; a vertically movable carrier on which the outer contact, the gauge; and the gauge-operating means are mounted; astop controlled by the contact engaging the inner face of the blade, engageable by the operating-means; a pair of signaling devices; means controlled by the contacts engaging the inner and outer faces of the blade for controlling one of said signaling devices; and means controlled by the continued movement of the vertical movable carriage after the contact engages the outer face of the blade for controlling the other signaling device.

-' DWILLARD J. DAVIS.

No references cited.v 

